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Frank Visser, graduated as a psychologist of culture and religion, founded IntegralWorld in 1997. He worked as production manager for various publishing houses and as service manager for various internet companies and lives in Amsterdam. Books: Ken Wilber: Thought as Passion (SUNY, 2003), and The Corona Conspiracy: Combatting Disinformation about the Coronavirus (Kindle, 2020).

The Quicksand Cathedral

A Devastating Critique of Bernardo Kastrup's Analytic Idealism

Frank Visser / Grok

Bernardo Kastrup erects a metaphysical cathedral whose spires pierce the clouds of consciousness studies, yet the entire edifice rests on quicksand. His analytic idealism—sold as the parsimonious salvation of metaphysics—promises to dissolve the hard problem, reconcile science with meaning, and restore ontology to its rightful mental ground. Instead, it multiplies mysteries, inverts evolution, and collapses under the weight of its own contradictions.

What begins as a daring inversion of physicalism ends in a theological halfway house: a cosmic Mind-at-Large that is less conscious than we are, a dissociation analogy that fails at every scale, and a promise of life after death that is nothing but ego-annihilation in a pre-personal soup. Even Alex O'Connor, the razor-sharp host of Within Reason—a skeptic whose interrogations have dismantled theistic apologetics and vegan dogmas alike—emerges from his 2025 dialogue with Kastrup intrigued, conceding ground on the mental nature of reality with an ease that belies his usual ferocity.

This is the seduction: Kastrup's eloquence ensnares even the vigilant. Below, the cathedral is razed, beam by beam, exposing why O'Connor's dalliance is a philosopher's flirtation with fog, and why the "mental" thesis dissolves into the question: Whose mind?

I. The Inversion Paradox: A Cosmic Mind Less Evolved Than Its Fragments

Kastrup's central thesis is Kantian in structure but Vedantic in flavor: the noumenon, the thing-in-itself, is mental. Not your mind, not mine, but a transpersonal Mind-at-Large whose excitations appear to us as the physical world. This universal field, he insists, is the ontological ground. Yet by his own metric—borrowed from Integrated Information Theory (IIT)—consciousness scales with causal integration (F). Human brains sit near the apex: reflective, linguistic, meta-cognitive. Mind-at-Large, by contrast, is diffuse, non-reflective, non-self-aware. It does not know itself; it merely excites.

Here is the first crack in the foundation: the ground state is less evolved than its derivatives. Evolution, Kastrup claims, is the universal mind's strategy to “explore itself” or “reduce entropy.” But evolution increases complexity and self-awareness. If Mind-at-Large is primordial, it is the least complex, least conscious state. Dissociation, then, is not exploration—it is devolution. The cosmic mind is a metaphysical vegetable, and we are its overachieving tumors. Kastrup's thermodynamics are upside-down: he requires a global decrease in entropy (more integration in alters) without a mechanism. Quantum vacuum fluctuations, his favored analogy, are symmetry-breaking events that increase local order at global cost. A non-reflective field spontaneously generating reflective sub-minds is like the vacuum birthing a philosopher. The physics is absent; only poetic hand-waving remains.

O'Connor, ever the empiricist, probes this in their exchange: "Can we conceive a world without minds?" Kastrup parries with parsimony—mentality is the only known, so extend it universally. O'Connor nods along, granting the analogy's pull, but misses the inversion: if the cosmic mind is "primitive," why posit it as prior? Whose mind is this—yours, in a solipsistic swell, or a collective hallucination? The thesis begs the bearer.

II. The Local Failure: Objective Idealism Without a Perpetual Perceiver

Kastrup rejects subjective idealism with vehemence. The Amazon rainforest predates human minds; the cosmic microwave background is 13.8 billion years old. This is objective idealism: a real world independent of any particular perceiver. Yet objective idealism demands a perpetual perceiver to sustain that world. Berkeley had God; Kastrup has Mind-at-Large. Every quark, every photon, every gravitational wave must be experienced by the universal field to be rendered real. This is panexperientialism on steroids—except the experiences are contentless. Mind-at-Large does not reflect, does not conceptualize, does not remember. Its “experiences” are pure, undifferentiated affection: a cosmic itch without an itcher.

Kastrup has smuggled in a zombie. He calls it mental, but it is affect without subject, qualia without qualia-bearer. The category error is glaring: if mentality is defined by reflection, narrative, or intentionality, Mind-at-Large fails the test. If mentality is mere affection, then rocks and rivers are mental by the same token—panpsychist sludge. Either way, the universal mind is either too conscious (a hidden God) or not conscious enough (a metaphysical appendix). Realism, by contrast, needs no cosmic perceiver. The world persists because physical states persist. No turtles required.

O'Connor accepts this "all things mental" framing too readily, perhaps because Kastrup frames it as the "extrinsic image" of a unified field—aligning with quantum non-locality and IIT's holistic bent. But whose mind? If it's "transpersonal," it evades personal accountability; if it's ours collectively, it risks solipsism. O'Connor, trained in analytic precision, concedes the monism's elegance without demanding: Who dreams the dreamers? The ease betrays a skeptic's soft spot for meaning-making over mechanism.

III. The Dissociation Analogy: A Category Mistake Masquerading as Science

Kastrup's master metaphor is Dissociative Identity Disorder (DID). You and I are alters—subpersonalities—of Mind-at-Large, just as trauma fragments a single psyche into multiple identities. The analogy is seductive until scrutinized. In DID, alters share one brain, one body, one sensory stream. They compete for executive control; amnesia barriers are neural firewalls. Kastrup's cosmic DID has no shared substrate. Human minds are causally sealed from each other's qualia, yet allegedly dissociated from the same field. Where is the executive center? Who “fronts” when I sleep and a dog wakes? Trauma-induced splits take hours; Kastrup's splits take geological epochs. The analogy is not psychology scaled up—it is theology in a lab coat.

The boundary problem compounds the farce. A mind, per Kastrup, requires high internal integration (F) and a Markov blanket. But nature abhors clean cut-offs. Is a bee an alter? A nematode? A biofilm engaged in quorum sensing? The biosphere itself? Kastrup has no principled threshold. The Sorites Paradox swallows him whole: grant a human alter, and you must grant alters within alters—liver cells dissociating from brains, neurons from ganglia. Boundaries dissolve into panpsychist goo. Realism draws a clean line: minds emerge from brains with sufficient neural complexity. No cosmic alters, no metaphysical blankets.

O'Connor presses on the self's illusion but yields to the DID parallel, finding it "fascinating" for explaining intersubjectivity without dualism. Why the buy-in? Kastrup's rhetoric—aggressive yet empirical—flatters the intellect, reviving idealism as "analytic" rather than mystical. Yet it raises the ghost: whose mind hosts these alters? A non-reflective overlord, or our fragmented psyches projecting upward?

IV. The Moral Body Problem: Dashboard or Dwelling?

Your body, Kastrup says, is the extrinsic appearance of your alter's intrinsic metabolism. Transplant the brain, and the alter moves with it. The dashboard is disposable. Why, then, does torture matter? If I am not my body, why is pain morally salient? Conjoined twins share a body but have two brains—whose metabolism is whose? Split-brain patients generate conflicting beliefs from severed hemispheres. Is this one alter with internal conflict or two alters in one skull? Kastrup's answers are vague gestures toward “partial boundaries.” Realism is crisp: two brains, two minds, one body. Embodiment is not a metaphor; it is identity.

V. Life After Death: Annihilation in a Pre-Personal Soup

Kastrup's eschatology is the cruelest bait-and-switch. Death, he promises, is de-dissociation: your alter merges back into Mind-at-Large. But Mind-at-Large is non-reflective, non-linguistic, non-personal. Your memories, identity, and loves dissolve into diffuse affection. This is not survival—it is obliteration. Calling it “life after death” is semantic fraud. Realism offers no false hope: consciousness ends when the brain does. The choice is stark: honest finitude or cosmic lobotomy.

O'Connor, haunted by mortality's sting, lingers on this—Kastrup's "meaningful universe" resonates with a podcaster who has dissected atheism's void. The acceptance flows from existential balm: if all is mental, death is reunion, not rupture. But whose mind awaits? A benevolent field, or our own echo?

VI. The Explanatory Regress: Why Stop at One Mind-at-Large?

If dissociation explains individual minds, why not dissociation within Mind-at-Large? Perhaps it is itself an alter of a Mind-at-Larger. Kastrup's stop-rule—“it's the ground”—is assertion, not argument. Realism halts at physical laws. No infinite turtle stack.

VII. Realism's Clean Slate: Subtraction Over Superstition

Realism wins by subtraction. It removes the cosmic middleman and his baggage.

VIII. The Great Bypass

Kastrup strides onto every stage proclaiming that idealism “dissolves” the hard problem the way a magician dissolves a rabbit: with a flourish and a hidden trapdoor. The trick is childishly simple. Physicalism asks, “How does dead matter light the lamp of experience?” Kastrup answers, “There was never any dead matter; the lamp was always on.” He then bows to thunderous podcast applause, as if renaming the mystery has abolished it. In truth he has performed the philosophical equivalent of declaring bankruptcy to erase debt: the correlation between brain states and feelings remains exactly as stubborn, exactly as law-like, and exactly as unexplained as before. He has merely relocated the invoice from the physics department to the metaphysics mailroom and stamped it “Return to Sender.”

Ask him the only question that matters—“By what rule does this particular ripple in Mind-at-Large look like forty hertz of gamma synchrony in the cortex, while that ripple looks like the smell of burnt toast?”—and the oracle goes mute. The brain, he intones, is the “externalisation” of the mind, the way a dream-body is the externalisation of a dream-thought. Lovely metaphor; zero mechanism. No field equation, no bridge law, no predictive function links the felt throb of anger to the red blob on the fMRI. “Externalisation” is the promissory note Kastrup issues whenever the cashier asks for cash. In physics such a note would be laughed out of the building; in idealism it is framed and hung above the mantelpiece. The hard problem stands in the corner, unchanged, wearing a new hat and smirking.

Worse: the bypass is a one-way street that loops straight into regress. If the brain is the image of the mind, who is looking at the image? Mind-at-Large, presumably. But then the cosmic field must contain its own dashboard—an infinite stack of scanners scanning scanners, each “externalising” the one above. Kastrup never notices the turtles piling up beneath him because he is too busy admiring the view from the balcony. Realism, by contrast, needs no infinite mirrors: brains evolved, feelings tag along, correlations are discovered rather than decreed, and the mystery—though still a mystery—comes with a research program instead of a slogan. Kastrup's cathedral does not dissolve the mind-body problem; it entombs it in stained glass and charges admission.

IX. Why O'Connor Falls: The Siren's Call of Elegant Despair

O'Connor's susceptibility is no anomaly; it's the idealism trap for the brilliant. A Cambridge-trained philosopher, he wields Occam's razor like Excalibur, yet Kastrup's blade is sharper in the dim light of materialism's failures. The hard problem gnaws: why does neural fizz feel like anything? Kastrup's retort—mentality as primitive, not emergent—lands like revelation, especially when buttressed by IIT and quantum analogies O'Connor knows well. He accepts "all things mental" because it unifies: no zombie substrate, just a dashboard of the divine. But the ease conceals the sleight—whose mind? Kastrup's "transpersonal" dodge evades solipsism while flirting with it, a non-theistic God for atheists weary of nihilism.

Online whispers confirm: Reddit skeptics decry Kastrup's "aggressive rhetoric" propping lazy arguments, yet praise his revival of idealism as "approachable." O'Connor, post-dialogue, admits the "counterintuitiveness" but concedes its parsimony, perhaps swayed by Kastrup's personal gravitas—a computer scientist turned mystic, echoing O'Connor's own pivot from vegan advocacy to metaphysical hunts. It's the allure of coherence in chaos: if reality is mental, suffering has a dreamer. Yet this comforts at the cost of clarity. Realism demands no such whose—minds are local, emergent, finite. No cosmic landlord required.

O'Connor's nod to the mental whole is the idealist's honeyed hook: elegant, yes, but whose banquet? The dissociation analogy is not a solution; it is the mother of all problems. Kastrup's cathedral is magnificent, but it is built on quicksand. When the tide of scrutiny rises, the spires sink, and realism stands on solid ground—minds finite, worlds persistent, no whose to haunt the dawn.

Professional Philosophers' Reflections on Bernardo Kastrup's Analytic Idealism

Bernardo Kastrup's analytic idealism—positing that reality is fundamentally a universal "mind-at-large" (a non-anthropomorphic, transpersonal consciousness) whose excitations manifest as the physical world—has gained traction in popular philosophy circles, podcasts, and online discussions. His PhD dissertation (defended in 2019 at Nijmegen University, titled Analytic Idealism: A consciousness-only ontology) formalizes this view, drawing on empirical data from neuroscience, quantum mechanics, and integrated information theory (IIT) to argue for mental monism over physicalism. However, while Kastrup is prolific in public forums (e.g., debates with Alex O'Connor, Curt Jaimungal, and appearances on Theories of Everything), his ideas remain a niche, minority position in academic philosophy. Only about 6% of philosophers self-identify as idealists in recent surveys like PhilPapers (2020), and Kastrup's version is often seen as a bold but fringe revival of post-Kantian idealism, blending analytic rigor with Eastern non-dualism.

Professional philosophers have engaged with his work, though not extensively or uniformly positively. Engagement is sporadic—more in journals like Philosophies and Journal of Consciousness Studies than in top-tier outlets like Mind or Nous. Critics appreciate his critique of physicalism's "hard problem" (echoing David Chalmers) but fault the theory for explanatory gaps, unfalsifiability, and over-reliance on analogies like dissociative identity disorder (DID) for cosmic-scale individuation. Below, I outline key reflections, starting with Chalmers and branching to others. This is based on citations, debates, reviews, and public statements up to November 2025.

David Chalmers: Sympathetic Citation and Implicit Endorsement

David Chalmers, the philosopher who coined the "hard problem of consciousness" in 1995, has the most prominent (though indirect) engagement with Kastrup. In his 2019 paper "Idealism and the Mind-Body Problem" (published in Philosophy Now and expanded in later talks), Chalmers explicitly cites Kastrup's work as a "potentially promising" form of idealism that could resolve the explanatory gap between physical processes and subjective experience. Chalmers argues that idealism (including Kastrup's analytic variant) is "as strong as any position" on the mind-body problem, praising its parsimony: it treats consciousness as fundamental rather than emergent, avoiding physicalism's "zombie" metaphysics (unconscious matter magically producing qualia).

Context and Nuance: Chalmers doesn't fully endorse Kastrup but uses him to illustrate how idealism sidesteps panpsychism's "combination problem" (how micro-minds fuse into macro-minds). He notes Kastrup's DID analogy—where individual minds are "dissociated alters" of mind-at-large—as a clever empirical hook, though he doesn't address its scalability (e.g., to non-human entities). In a 2017 NYU Shanghai workshop organized by Chalmers (mentioned in Kastrup's reflections), they reportedly exchanged ideas, with Chalmers appreciating the "analytic" framing that makes idealism palatable to Anglophone philosophers. bernardokastrup.com

Limitations: Chalmers remains agnostic, favoring property dualism or panpsychism personally. He critiques idealism broadly for struggling with intersubjective consistency (why does mind-at-large "agree" on shared perceptions?). No direct rebuttal to Kastrup, but in 2023 Reddit discussions among philosophers, Chalmers is invoked as a "bridge" figure who elevates Kastrup without committing.

Kastrup often credits Chalmers as an influence—his "eureka" moment came reading Chalmers' 1995 paper—positioning analytic idealism as a "Chalmersian" solution to the hard problem. They shared a 2022 panel at the HowTheLightGetsIn festival with Patricia Churchland (a physicalist), highlighting Kastrup's respectability in mixed forums.

Other Professional Philosophers: Mixed Critiques and Engagements

Kastrup's work has elicited responses from a range of philosophers, often in response to his critiques of physicalism and panpsychism. Here's a table summarizing key figures, their stances, and representative works (focusing on post-2017 reactions to his mature analytic idealism):

Broader Academic Reception

Positive Signals: Kastrup's papers appear in peer-reviewed venues (Philosophies 2017; SAGE Open 2018), and he's cited in consciousness anthologies. Chalmers' nod gives legitimacy, positioning him as a "serious" idealist amid panpsychism's rise (e.g., Strawson, Goff). Online forums like r/askphilosophy (2025 threads) debate him as "legit but niche," not "trolling." X discussions (e.g., semantic searches for "philosophers discussing Kastrup") show enthusiasm from figures like Neil Rushton (esoteric philosopher) but little from A-list academics.

Criticisms: Common themes include the "decombination problem" (Wikipedia entry on hard problem critiques Kastrup's DID fix as insufficient for cosmic scales). Felipe Bautista's 2024 Medium essay calls it "dogmatic metaphysics" ignoring Kant's limits on knowledge. Overall, it's viewed as eloquent but not paradigm-shifting—more a public stimulant than academic staple.

Why Limited Engagement? Kastrup's emphasis on popular media (books like The Idea of the World, 2019) over dense tomes may sideline him in ivory towers. As one r/consciousness user notes, "Most criticisms are strawmen from materialists misunderstanding metaphysics." Yet, as Timothy Williamson laments in a 2025 X post, philosophy's "pretentious abstraction" can dismiss simple rebuttals, mirroring Kastrup's own charge against physicalism.

In sum, yes—Chalmers and others reflect on it thoughtfully, but as a provocative outsider theory rather than consensus-builder.